| 1 | ;;; china-util.el --- utilities for Chinese |
| 2 | |
| 3 | ;; Copyright (C) 1995 Electrotechnical Laboratory, JAPAN. |
| 4 | ;; Licensed to the Free Software Foundation. |
| 5 | |
| 6 | ;; Keywords: mule, multilingual, Chinese |
| 7 | |
| 8 | ;; This file is part of GNU Emacs. |
| 9 | |
| 10 | ;; GNU Emacs is free software; you can redistribute it and/or modify |
| 11 | ;; it under the terms of the GNU General Public License as published by |
| 12 | ;; the Free Software Foundation; either version 2, or (at your option) |
| 13 | ;; any later version. |
| 14 | |
| 15 | ;; GNU Emacs is distributed in the hope that it will be useful, |
| 16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | ;; GNU General Public License for more details. |
| 19 | |
| 20 | ;; You should have received a copy of the GNU General Public License |
| 21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the |
| 22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| 23 | ;; Boston, MA 02111-1307, USA. |
| 24 | |
| 25 | ;;; Commentary: |
| 26 | |
| 27 | ;;; Code: |
| 28 | |
| 29 | ;; Hz/ZW encoding stuffs |
| 30 | |
| 31 | ;; HZ is an encoding method for Chinese character set GB2312 used |
| 32 | ;; widely in Internet. It is very similar to 7-bit environment of |
| 33 | ;; ISO-2022. The difference is that HZ uses the sequence "~{" and |
| 34 | ;; "~}" for designating GB2312 and ASCII respectively, hence, it |
| 35 | ;; doesn't uses ESC (0x1B) code. |
| 36 | |
| 37 | ;; ZW is another encoding method for Chinese character set GB2312. It |
| 38 | ;; encodes Chinese characters line by line by starting each line with |
| 39 | ;; the sequence "zW". It also uses only 7-bit as HZ. |
| 40 | |
| 41 | ;; ISO-2022 escape sequence to designate GB2312. |
| 42 | (defvar iso2022-gb-designation "\e$A") |
| 43 | ;; HZ escape sequence to designate GB2312. |
| 44 | (defvar hz-gb-designnation "~{") |
| 45 | ;; ISO-2022 escape sequence to designate ASCII. |
| 46 | (defvar iso2022-ascii-designation "\e(B") |
| 47 | ;; HZ escape sequence to designate ASCII. |
| 48 | (defvar hz-ascii-designnation "~}") |
| 49 | ;; Regexp of ZW sequence to start GB2312. |
| 50 | (defvar zw-start-gb "^zW") |
| 51 | ;; Regexp for start of GB2312 in an encoding mixture of HZ and ZW. |
| 52 | (defvar hz/zw-start-gb |
| 53 | (concat hz-gb-designnation "\\|" zw-start-gb "\\|[^\0-\177]")) |
| 54 | |
| 55 | (defvar decode-hz-line-continuation nil |
| 56 | "Flag to tell if we should care line continuation convention of Hz.") |
| 57 | |
| 58 | (defconst hz-set-msb-table |
| 59 | (let ((str (make-string 127 0)) |
| 60 | (i 0)) |
| 61 | (while (< i 33) |
| 62 | (aset str i i) |
| 63 | (setq i (1+ i))) |
| 64 | (while (< i 127) |
| 65 | (aset str i (+ i 128)) |
| 66 | (setq i (1+ i))) |
| 67 | str)) |
| 68 | |
| 69 | ;;;###autoload |
| 70 | (defun decode-hz-region (beg end) |
| 71 | "Decode HZ/ZW encoded text in the current region. |
| 72 | Return the length of resulting text." |
| 73 | (interactive "r") |
| 74 | (save-excursion |
| 75 | (save-restriction |
| 76 | (let (pos ch) |
| 77 | (narrow-to-region beg end) |
| 78 | |
| 79 | ;; We, at first, convert HZ/ZW to `euc-china', |
| 80 | ;; then decode it. |
| 81 | |
| 82 | ;; "~\n" -> "\n", "~~" -> "~" |
| 83 | (goto-char (point-min)) |
| 84 | (while (search-forward "~" nil t) |
| 85 | (setq ch (following-char)) |
| 86 | (if (or (= ch ?\n) (= ch ?~)) (delete-char -1))) |
| 87 | |
| 88 | ;; "^zW...\n" -> Chinese GB2312 |
| 89 | ;; "~{...~}" -> Chinese GB2312 |
| 90 | (goto-char (point-min)) |
| 91 | (setq beg nil) |
| 92 | (while (re-search-forward hz/zw-start-gb nil t) |
| 93 | (setq pos (match-beginning 0) |
| 94 | ch (char-after pos)) |
| 95 | ;; Record the first position to start conversion. |
| 96 | (or beg (setq beg pos)) |
| 97 | (end-of-line) |
| 98 | (setq end (point)) |
| 99 | (if (>= ch 128) ; 8bit GB2312 |
| 100 | nil |
| 101 | (goto-char pos) |
| 102 | (delete-char 2) |
| 103 | (setq end (- end 2)) |
| 104 | (if (= ch ?z) ; ZW -> euc-china |
| 105 | (progn |
| 106 | (translate-region (point) end hz-set-msb-table) |
| 107 | (goto-char end)) |
| 108 | (if (search-forward hz-ascii-designnation |
| 109 | (if decode-hz-line-continuation nil end) |
| 110 | t) |
| 111 | (delete-char -2)) |
| 112 | (setq end (point)) |
| 113 | (translate-region pos (point) hz-set-msb-table)))) |
| 114 | (if beg |
| 115 | (decode-coding-region beg end 'euc-china))) |
| 116 | (- (point-max) (point-min))))) |
| 117 | |
| 118 | ;;;###autoload |
| 119 | (defun decode-hz-buffer () |
| 120 | "Decode HZ/ZW encoded text in the current buffer." |
| 121 | (interactive) |
| 122 | (decode-hz-region (point-min) (point-max))) |
| 123 | |
| 124 | ;;;###autoload |
| 125 | (defun encode-hz-region (beg end) |
| 126 | "Encode the text in the current region to HZ. |
| 127 | Return the length of resulting text." |
| 128 | (interactive "r") |
| 129 | (save-excursion |
| 130 | (save-restriction |
| 131 | (narrow-to-region beg end) |
| 132 | |
| 133 | ;; "~" -> "~~" |
| 134 | (goto-char (point-min)) |
| 135 | (while (search-forward "~" nil t) (insert ?~)) |
| 136 | |
| 137 | ;; Chinese GB2312 -> "~{...~}" |
| 138 | (goto-char (point-min)) |
| 139 | (if (re-search-forward "\\cc" nil t) |
| 140 | (let (pos) |
| 141 | (goto-char (setq pos (match-beginning 0))) |
| 142 | (encode-coding-region pos (point-max) 'iso-2022-7bit) |
| 143 | (goto-char pos) |
| 144 | (while (search-forward iso2022-gb-designation nil t) |
| 145 | (delete-char -3) |
| 146 | (insert hz-gb-designnation)) |
| 147 | (goto-char pos) |
| 148 | (while (search-forward iso2022-ascii-designation nil t) |
| 149 | (delete-char -3) |
| 150 | (insert hz-ascii-designnation)))) |
| 151 | (- (point-max) (point-min))))) |
| 152 | |
| 153 | ;;;###autoload |
| 154 | (defun encode-hz-buffer () |
| 155 | "Encode the text in the current buffer to HZ." |
| 156 | (interactive) |
| 157 | (encode-hz-region (point-min) (point-max))) |
| 158 | |
| 159 | ;; |
| 160 | (provide 'china-util) |
| 161 | |
| 162 | ;;; china-util.el ends here |